Monobore wells have a constant diameter for a given interval that is made up of multiple strings. Typically the existing string has an enlarged segment or bell into which the next string will be supported and then sealed after cementing, in the case of cemented wellbores. The newly added string has to be expanded and in some applications cemented and there needs to be a bell at the lower end of the added string so as to accommodate the next string and retain the monobore nature of the wellbore. The liner is first supported in the bell of the existing string leaving gaps to allow fluid displacement during cementing and those gaps are closed after cementing is completed.
The general description of the above procedure is optimized by finding ways to perform the needed steps to deliver, support, expand, cement and seal the liner to an existing tubular in as few trips as possible and ideally in a single trip.
One attempt at such a method is described in US Publication 2010/0032167. In one technique in this reference the swage assembly is pumped in a downhole direction for part of the expansion until a cement shoe is tagged. The running string is rejoined to the swage assembly for cementing. Subsequently the swage assembly is driven uphole to support and seal the newly added liner that had previously been supported from the hole bottom. After that the shoe has to be drilled out. There is no discussion of how the lower end of the recently cemented liner is to be belled out because the method described there is not for making a monobore but rather reduces the well diameter with each successive string. In an alternative embodiment the swage assembly is built just above the cement shoe and driven uphole to expand the liner. After cementing with the running string and swage assembly latched to the shoe, the swage assembly is released from the shoe and propelled with pressure from below while retained to the running string to finish the expansion at the liner top to secure and seal the liner to the existing tubular.
Various techniques have been developed to expand liners and attach them to existing casing already in the wellbore. Some of these techniques involve running a liner with a wide bell at the bottom where the expansion equipment is located and then driving the swage up the liner and out the top and along the way setting external seals to the surrounding casing as the swage makes an exit. One such process is shown in U.S. Pat. No. 6,470,966. The extensive list of prior art included in that patent is representative of the state of the art in downhole tubular expansion techniques that include attachment to an existing tubular. Other patents show the use of swages that include a series of retractable rollers that can be radially extended downhole to initiate a tubular expansion such as of a casing patch as for example is illustrated in U.S. Pat. No. 6,668,930. Some devices swage in a top to bottom direction as illustrated in U.S. Pat. No. 6,705,395.
Another approach is illustrated in an application entitled Pump Down Swage Expansion Method (by some of the inventors of this application) filed Oct. 8, 2010 and having a Ser. No. 12/901,122. That application uses a running string and liner peripheral seals to move a swage assembly for gaining liner support. It continues in that mode with building another swage after support of the liner in the existing tubular. In the same trip the shoe is secured and the liner cemented followed by engaging the seal of the liner hanger with manipulation of the running string. The swage assembly remains connected to the running string during expansion.
Methods that mechanically advance a swage through a tubular require the rig equipment to not only support the weight of the string to be expanded but also to be able to handle the applied force to the swage to advance it through the tubular to enlarge the diameter. This reference, identified in the previous paragraph, reduces the surface equipment capacities needed to perform an expansion to complete a well. The method features a top down expansion using a plurality of adjustable swages that get built at different times and that are driven from applied annulus pressure delivered around a workstring. The tubular to be expanded is placed in an overlapping position with an existing tubular. The swage assembly is pushed on a guide extending from the running string by virtue of a cup seal around the running string and another peripheral seal on the top of the liner to be expanded to prevent pressure bypassing as the swage assembly is run into the liner string to support the liner without sealing it. A further swage is built in the liner at a location below the support point to the existing liner and the balance of the liner is expanded to bottom while engaging the cement shoe as the swage assembly leaves the lower end of the now expanded liner. The shoe is repositioned and set at the lower end of the expanded liner and a cement job follows with a subsequent reversing out of excess cement. The swage assembly is pulled through the liner and another swage is built before it is pushed down through the liner top to set the seal of the liner hanger or optionally to go though past the slips of the liner hanger to create a constant drift though the expanded liner top. The assembly is removed.
Monobore applications using expansion have integrated cementing through a shoe while covering a recess at the end of an existing string with a removable cover that comes off after cementing. A string with a swage is placed in position and the swage is energized to grow in diameter before being advanced through the newly added tubular until the swage exits the top of the added tubular to fixate it into the recess at the lower end of the existing tubular. The result is a monobore well. These designs have also disclosed a deployable shoe that can be delivered with the string prior to expansion and then tagged and retained as a swage moves through the string only to be reintroduced into the expanded string and sealingly fixated to it for the cementing operation. Examples of one or more of these method steps are illustrated in U.S. Pat. Nos. 7,730,955; 7,708,060; 7,552,772; 7,458,422; 7,380,604; 7,370,699; 7,255,176 and 7,240,731. Other patents relating to expansion by moving a cone uphole from within a bell at a lower end of a liner to be supported to a recess in existing tubing and creating a monobore as well as expansion of tubulars downhole are as follows: 6,712,154; 7,185,710; 7,410,000; 7,350,564; 7,100,684; 7,195,064; 7,258,168; 7,416,027; 7,290,616; 7,121,352; 7,234,531; 7,740,076; 7,100,685; 7,556,092; 7,516,790; 7,546,881; 6,328,113; 7,086,475; 6,745,845; 6,575,240; 6,725,919; 6,758,278; 6,739,392; 7,201,223; 7,204,007; 7,172,019; 7,325,602; 7,363,691; 7,146,702; 7,172,024; 7,308,755; 6,568,471; 6,966,370; 7,419,009; 7,040,396; 6,684,947; 6,631,769; 6,631,759; 7,063,142; 6,705,395; 7,044,221; 6,857,473; 7,077,213; 7,036,582; 7,603,758; 7,108,061; 6,631,760; 6,561,227; 7,159,665; 7,021,390; 6,892,819; 7,246,667; 7,174,964; 6,823,937; 7,147,053; 7,299,881; 7,231,985; 7,168,499; 7,270,188; 7,357,190; 7,044,218; 7,357,188; 7,665,532; 7,121,337; 7,434,618; 7,240,729; 7,077,211; 7,195,061; 7,198,100; 6,640,903; 7,438,132; 7,055,608; 7,240,728; 7,216,701; 6,604,763; 6,968,618; 7,172,021; 7,048,067; 6,976,541; 7,159,667; 7,108,072 and 6,55,7640.
What is needed and provided by the method of the present invention is a way to introduce a string with a cementing shoe into a wellbore with an existing tubular with a lower end bell and add strings in a monobore completion where each string can be supported, expanded, optionally cemented and sealed to the bell of the existing tubular while leaving a lower end bell on the recently added tubular so that the process can be repeated for the particular zone or interval. Those skilled in the art will more readily appreciate additional aspects of the invention from the detailed description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention is to be determined from the literal and equivalent scope of the appended claims.